NURSUPIAMIN, Nursupiamin. Pengembangan Kajian Angka 19. Al-Khwarizmi : Jurnal Pendidikan Matematika dan Ilmu Pengetahuan Alam, [S. l.], v. 3, n. 1, p. 9–20, 2018. DOI: 10.24256/jpmipa.v3i1.215. Disponível em: https://ejournal.iainpalopo.ac.id/index.php/al-khwarizmi/article/view/215. Acesso em: 26 aug. 2025.